Jump to content
SAU Community

HELP!! Missing above 4000RPM

Ronin 09

By Ronin 09,
in Engines & Forced Induction

 Share

Recommended Posts

Ronin 09 Grand Master

Ronin 09

Posted
Posted

Hey everyone,

I did an engine, gearbox and diff oil change today on my R33 gtst, and took it out for a spin tonight. It was running really nicely, but when i took it above about 4500 RPM in mainly second it would hesitate, as if it was hitting a rev limiter or something.

It lost power but continued revving, but would miss - sounded like a braaaap! noise.

As a bit of background, all i have is a turbo back exhaust and air filter. Last dyno it was running peak boost of about 10.5PSI.

Its just a bit worrying and would like to get it sorted ASAP in case i am doing damage :D

Link to comment
https://www.sau.com.au/forums/topic/17705-help-missing-above-4000rpm/
Share on other sites
Cubes Grand Master

Cubes

Posted
Posted

First I would pull the plugs out and check them for hairline cracks in the ceramic. Then Check their gaps.

Slap them back in and if you still have a miss either you have a dud coil or there is a hairline fracture in the plugs that you missed.

I had a similiar problem where it would drive nicely then at around 4000rpm+ it would start to pull then braaappppp brap brapp then if I held it down it would kind of smooth out and start pulling again. Generally once over 6000rpm to 7000rpm would be ok.. It turned out a hairline fracture in the spark plug. I had cracked it when slapping in No. 5 cyclinder spark plug as I tried to use a swivel and not remove the engine pipe across the engine.. SO if you do spark plugs don't do it the easy way and use a swivel remove the engine pipe so you have 180degree access to the spark plug. Otherwise you risk cracking the ceramic.

I had the plugs in and out around 4-5times before I found the problem.

Cubes Grand Master

Cubes

Posted
Posted

I think meggala's www site has a bit of info regarding using a multimeter to check them

Also check the springs that contact with the top of the sparky. If they are burnt or black chances are they are rooted. You can patch this up sometimes by removing that spring and using one from a pen. So i've read.. Don't know if it works or not though.

Cubes Grand Master

Cubes

Posted
Posted

I would be very very wary of doing that.. Have you ever been booted by an electronic ignition? I have it doesn't feel very nice.

I couldn't believe the boot it gave me actually. I've been booted by mains before and it was very close to that i can tell you.

  • 3 weeks later...
anish maharaj Newbie

anish maharaj

Posted
Posted

hey guys i have the same issue (96 s2) put a boost controoler on it boosted to 0.7 bar to be safe and car felt like crap..really jerky..winded boost back down and the problem kinda went.. but a mate/mechanic looked at it and said coils or fuel is too lean... gets checked out on wed hopefully not too much of a drama..am concerned.. should I b?

Zahos Mentor

Zahos

Posted
Posted

It happens b/c the mixture gets way too rich, when you are running higher than stock boost.

Changing the plugs can help reduce the problem, but it wont fully go away until you sort your mixtures out!

I recently got my SAFC dyno tuned, and at around that point, I had my mixtures adjusted by -21%!!!!!! So as you can see, it was running MEGA rich there!!!! Now there is absolutely NO hesitation/misfire/spluttering at that point, just smooh driving all the way up to redline!

Th only plugs that helped me before my SAFC tune were NGK coppers: BCPR5E gapped at 0.7 ~ 0.8 mm, but like I said, it wont cure the prolem. If you go any colder than a heat range of 5 (>5) then you will see no improvement.

Just passing on what I have learnt from personal experience!

Zahos

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Predator1
      Tomei gasket

      By Predator1 · Posted

      Didnt realise RB's had more then 1 head.
    • MBS206
      Unpeeling the Orange

      By MBS206 · Posted

      I'm normally copping my own abuse from neglecting my daily drivers. "Those suspension bushes will last a bit more", "Don't worry about the oil leak, just keep topping it up". The project cars I'm always doing things slowly on them as I'm wanting them to be done better, and neater, and nicer. Luckily I don't have to deal with 18 year old Matt's "Learning to wire" stuff in the project cars. And there's only one piece of wiring I'm displeased about in the Landcruiser, and it's about to be cut out... However, the box loads of parts that have been going through this place lately for the Landcruiser... Brake pads Brake Rotors Full handbrake overhaul Wheel Bearings Seals Swivel hubs Steering Boxes Half the suspension joints Shocks Air bags (Ones to go in the rear springs for towing) Water pump Timing kit Lower timing case Harmonic Balancer Radiator Lots of other little seals and shits Gas struts for the bonnet New power window switches And god knows what else I've forgotten... Ha ha ha I have my fingers crossed the pinion seals don't start leaking on the diffs, that the transfer case doesn't leak, and the gearbox input shaft doesn't leak, nor the rear main seal. As they're about the only seals I haven't replaced in the driveline! I'm seriously eyeing off buying new caliper rebuild kits front and rear brake calipers... I'll probably recheck all the valve clearances soon too, and hopefully, it should be all good and sweet to haul some long distance trips again!
    • GTSBoy
      Unpeeling the Orange

      By GTSBoy · Posted

      Every time I pull my 3x gauges out of the console and see the crack-addict way that I did the wiring, and I just can't bring myself to tear it all apart and "make it nice", because it is currently working. In fact, the last time I was in there I probably made it worse.
    • Kinkstaah
      Unpeeling the Orange

      By Kinkstaah · Posted

      The best part is when you own the car long enough that you look back and find your OWN ham fisted amateur shit!
    • MBS206
      Unpeeling the Orange

      By MBS206 · Posted

      The annoying part about neglect, is when you start to replace one thing, and find ten more broken things. Ham fisted monkey repairs you normally only find out about when trying to do something unrelated! Ha ha   Neglect you can kind of anticipate the huge costs to fix it all. Ham fistedness is normally a shock the first time your work on a new old car, as everything "looked" good before.
×
×
  • Create New...